Any idea why they didn't go with the full blown LS9 setup? Seems to me if they wanted the true track sedan, the oil sump changes would of been quite beneficial.

I don't think they ever intended this to be a full-on track car. I mean really, who buys a large four door luxury car with serious track intentions? I would imagine that the dry sump only comes into play with extremely high cornering Gs that the Z06 and ZR1 are capable of. The C5 Z06 had some oil pressure issues in heavy track use that GM addressed with the C6. I'm guessing it will never be a problem on the Caddy, as it's not capable of those kind of cornering forces.